Television system



l 0er. 30,1928' A -iNvENToR K. Zwargk l BY llwlmssss: y I l,

ATTORNEY men-ts 'thereof into a picture at the receiving4 produce such com was: zwom-fsm.' es swissvam, PENNSYLVANIA. "moisson :no 'vr-naviazio-` 'Wirsn srnijss rare 'Hoces mornin e moraornnnio commer; a con-nommen or' reinicia'.

vasim. y

- .siannvisrozi avarizia. t

.espionage inca my ii, i927. serial no. 190,481.

AMy invention relates to picture-'transmis a plural-ity of lines in the-Sceneor in the resion systems and particularly to provisions prodiiced picture are traced during each for scanning the scene :it .the sendingstation revolution of the apparatus. and to provisions 'for re'combining the ele- It is a further obj-ect of my invention to und movement o station. ght path that its trace upon the scene, or on Many scanning and recombiningdevicesin the reproducing screen, will be a., spiral. the prior art are made dependin upon some It isa further object of my invention to rapidly movin possesses inertia, the mechanical considerathe s iraiwil not coincide butt at 'a later tions which have heretofore placed a limit spira wii1 never fall on exactly the location upon the rapidity of the movementhave preof nn earlier one. By this means, a. Y eater vented the use of systems including such dereproduction of detail is secured 'with the vices for television, because the time required saine number of lines per inch than-has herel5 for analysis by the scanning, device and for tofore been possible.

recombination in the reproducing device could not beniadc small enough to ermit lect those portions of said spiral inV which the transmission of a dozen ormore pictures the re reduction of the illumination is but per second.A y little c istortcd and -to reproduce the picture It is an object ofV m invention'to-provide by 'means osaid selected portions.

a Scanning device an .a recombining device It is a further ob'ect of my ignventionto in which siiiicient rapidity of operation. can provide rnefins'whcre y'said selected portions] be .obtained without requiring prohibitively 'of thcfspiral'inay he brought into superposed high speed 4"of movement of tjge frnovingj;position parts. It is a;

It is a further object of my invention to 'provi-defer said superposition 'by -niea'ns of provide .an-optical means wherebythe vbenin astationar o tical apparatus.

of light in' the recombiriing device 'at the re- It is n iirt ier 4object of my invention to ftheV clement If tis element ensure not onl that siiccessivere titio'ns of v'It is a further object of my invention to sefurther object of my invention ceiving Station or the corresponding opticall provide two rotating optical parts-driven l) l path in' :the scanning device may be ino-ved 'a common motor and -to provideadjustab e with a high rapidity-,although the movement means for causing the'speed-of rotation fof of the moving optical parts is only 'of modone of sai-d parts to differ from that of the etnie-speed. other by a controllable amount.

It a further object. of my invention to provide an optical device in 'which the only Y parent from theol-loi'ving detailed dcscri moving parts rotate about Vone .commonaxis tion and `the and do not extend to any verygreat distance which, from said exis, whereby ccntrifugalforccs Figure are reduced to a minimum form .of the rccombining apparatus.

It is a further object 'of my invention vto provide a, picture-transmission s 'stem of the of the'scannin-g apparatus. type-comprising rotating arts m which the Fig. 3 is espiral -illns'treting'the form of system can obtain the a' vantages' of com# thet'race of the light .path upon thesceneor pound lenses'. i upon the screen.

It is a further object of my .invention 'to provide such an `optical dev-ice in which the" principles employed inthe invention.

`ght path is caused tomake an angle lf witli Fig.-5 is a. front view and Fig. 6 is vaseosaid axis of rotation.- ion ofthe pri-soil shown near the middle of It is` a further object of my invention 'to Figa-i. lprovide means for varying'aforesaidangl'e.

It is a further object -of lmy invention Ato of the prism fo thespiral. 'provide stationary. optical means so coop- Fig. 8 is a dia-gram illustrating theeect eratng with the movable-optical meenstha't ofsaid prism.l

1 is a verticalsection through 'one Other objects of my invention Awill be ap# Fig..2 is a, vertiealsection through 'one forni Figa-4 is ii :diagrem illustrating the Opti-esl.

imil Figs is a front view ma rig. '1o is a sestion of an assemblage of prisms constitu-ting a. modification of the yprism illustrated in' Figs. 4 to 6.

,'Fig. 1l is a-f'liagam illustrating the rela-- tion of the assembled prisms lto the spiral and tho effect-of the prisms.

Fig. I2 is a diag-fram illmstratinf.,7 the optical principles involved inthat form of the in vention which employs the prisms shown in Figs. 9 and 10,

Fig. 13 is an optical diagram illustrating a modrficatio'n m which reflectors are used 1nvstead' of refractl-ng prisms; Fig. 13 is a dlagrammatic section upon the line 13.-13 of The light after passi-ng through the' two prisms impinges 'upon a screen 6. This may be a translucent screen, as illustrated, or it may be a. distant screen to be viewed by spectators in a room. In the form illustrated, thc

screen is mo'vabiy mounted, a bellows 7 being provided to accommodate the movement.

The prism 4 is mounted in the rotor 10 of a. motor, preferably of the squirrel-'cage type. Ball bearings 11 are provided for accurately centering the rotor relative to the stator 12 and for preventing rictional resistance to its movement.

The rotor has a central opening lined by a steel Atube 13 in which-the prism 4 is mounted. A. similar steel tube 1 4 in aliner-nent with the tube 13 carries the prism 5. Thisjftnbe is sup orted by a suppleinen tal rotor 15 supported t rough ball bearings 16'in a h ub 17 \vhic h is magnetically 'continuous with the stator12. The stator 12 is provided 'with the usual-wind 'ings for causing a rotating Held. y

The rotor 10 is preferably of the slotted type, withv sqnirrebcage conductors in the slots to ensure thatit will rotate in -synchronism with the rotating field established by the lwindings o 'f the-stator.- The rotor -15, however, is preferably unslotted and receives but little torque directly from the rotating field through-the hub`17. It does, however, receive a. torque by the magnet-ic drag between the telescoping portions 'of the tubes13 -and 14. If the very slight friction of the ball .bearin gs 16 were the-only load on rotor 1 5, this .inag- .netic draf: vwould be suiiicient to cause the two` rotors to be synchronous Ill-order that the rotor .shall not run at the saine speed as the rotor 10, the rotor 15 is provided v'ith n conductive 18, pree-rably "of al uni-inum which 2X-tends between the poles 'of apermanent magnet 19, adjusted by means of a screw 20. The action .of the rrmgnet upon .the disc scives to retard the 'prism 5. wh'e'rcl-ay ilh-zstrated in Fig. 2 n.ay equally well be apf plied to the reproducing device.'

The lcns 30,through which the scene is Afocased, is analogous in its posi-tion in the opti- .cal system of Fig. 2 to thescreen A6 in Fig. 1. rl'he lens 30 is preferably an achromatic lens'. The prism 31 is mounted in a rotor '32 justas the prism 4 is mounted in the rotor 10. T he stator 33 is provided with a projecting huh 34 supportingr a second rotor 35 for' moving a -sec ond prism 3G as the prism 5 in Fig. lis moved. The prism 3G is retarded by means of a conductingr disc 37 and an adjustable magnet 38 'corresponding to disc 18 and 4magnet 19` in.

Fig. 1.

The prisms 31'and 3G, instead 'of being provided with curved surfaces toact-as lenses, are ordinary 'prisms and the lens action is obtained by the lens 30. The lens 40 4at the right of the prisms is optically .analogous tothe lens 2 in Fig. l. It may be adjusted by means of screws' 41 for correcting the focus.

.A housing 42 which enclos'es the optical por-` `tion or' the apparatus is provided with an open end through which the screws 41 may bcreached for said adjustment.v A tht-'ngc 43 is provided at the right of the casing.,7 in order that the' apparatus which is pnt'in place after u the focusing performed 'shallbe definitely positioned.

The light-sensitive .apparatus which is to cooperate Awith thescannmg device 1s con tained in a housing one face of which abats again-st the flange '43, thereby fixing the dis tance of the apparatus from the lens 40 definitcly. A small window 45 in the housing admits light from the lens 40 to the lightsonsit-ive apparatus.

'll-he'xlighbsensitive appara-tus is represent ed as a photo-electriccell -46 combined with a. thermionie amplifier 47. be understood that the photorelectrc cell andthe amplifier can be separa-ted ifdesired and it will also be understood that. any other lighbsensitve. apparatus 'may 'be used if preferred.

The system by which the light #emittedfrom the lamp 1 is made to correspond inv intensityv to the illumination of the photo-I cell -46 lis not part of the present invention and,

therefore, is not described ign-detail.

Itv will, however,-

iso i les' 'System by mea-ns .of which, items by is.l

stent, the light supplied to the yreproducing apparatus is made to correspond to the illn. 'mination of the light-sensitive apparatus in the iight .finally reaches be considered as if it were a 'source of illumination, th imagmary light from said source will arrive at the point from -which'tlie real light actuallyV started- This principle will enable us .to de-- scribe the operation of Fig. 9. more convenientiy by tracing the li eht path backward, that is, by speaking as if the Windowl 45 were a source of light.v

The beam of light from the lamp 1 and the light v-erough the optical Asystem of Fig. 2 'p each travel' along a'light'path. Thesedight paths have many similarities nltiio'ugh, because the beam from the lamp travels its path in a. direction .opposite to that in which the light entering the window 45 travel-s its path, these similarities are not easily. expressed in Words.

In the .scanning device, the lenses 30 -end and the prisms 31 and 36 establish an optical path which at any instant connects some one point in the scene with the 'window 45 and so with the photo-cell 46.

The window 45 is at the -principal focus of the optical system comprising lenses 30' and 4.0. The window 45, however, does not oever the Whole iield of these lenses but only one spot, which is so small, relative to the fied, that :it may be'iegarded as an element of 'the scene.

The path from the 'window 45 through Athe lenses would, if it' were not for the prisms 3i and 36, reach the center of the. scene. The Aprisms 31 and 36 act to bend the path of light, whereby the window 45 is associated with a point at one side ot' the centerof the scene. I

When the-prisms 31- and 3G are in the relative position illustrated inv Fig. 2, the diwetting action of one prism isl added to the diverting action of the other pris-m with the result that., 'as the prisms rotate together, the trace of the .optical path upon the scene is a circle of large diameter.

Since the'prism 36 rotates at a smaller v-e locity than-the prism 31. the tw@ prisms will not eontinue'tobe in the relative position illustrated in Fig. 2 and 'they will sooner o: later arrive at a relative position in which the diverting action of one vprism is ea-ctly opposite that'of the other. 'If the two divel-ting actions are equal, the resultant diversion of the 'light path is then zero and eiewinaow 45 ein be @prawny @seated n 'to the eenterof .the scene.

-As the relative position of the prisms and 36clmnges gradually fromA that illustratcd in Fig. 2 to that in `which there is zero diversion, the trace o the optical pathfupon the scene-- will be 'a spiral.

The ouh-nest whorl ofthe spinal will' correspond to the relative position illustrated in Fig'. 2 and the 'innermost Whorl or the-central point will 'correspond to the position in which there is minimum or zero diversion. The

spiral 'fas a whole will, therefore, cover the.

whole scene.

Any one'whorl of the spiral will be traced in thetime-rcquired fox-'one revolution of the motor. The whole spiral willbe traced' from the outer whorl to the center in the time required for the prism 36 to lagbehind lthe prism 31, one-half of a revolution.

During' the time that the prism 36 lags, an additional half-revolution Abehind the risrn 31, the spiral will be traced from the center to the outmost whorl. The whole picture is, therefore, covered twice in the time required tor a single complete revolution of one prism relative to the' other. If, for example` the prism 36 rotates eight turns per 'second slower than the prism 31. there will be sixteen complete explora-tions of the sce-ne per second.

The spiral vtraced 'from -thecenter outward will not coincide with that vtraced inward. To clearly show this the first few .whvorls of. the spiral Vwhich begins at the center are shownin dotted vlinesin Fia. 3.

If'the number of .revoiutions per second by which the of the prism 31 differs from that of the prism 36 isnot a 'whole number',

the. spiral traced hv the optical path from the center outward will not coincide with the next spiral traced in the same direction. spiral traced during Aany one half-period of the relative rotation will correspond with a previous' spiral traced e. nm-nher ot periods of .the relative rotation earlier e'qual'to the denominator of the fraction exnressing the of revolution differs 4frornthe other.

" Moreover, if `the rate of revolution of one there fore, evidentthat by properly adjusting. the magnet 38, the scanning device may be' made to explo-re the Whole picture. instead of merely espion-irrer certain imes.

The'- l lnumber oturns per second by .which `one rate there will ncverbe'- Fonsider the combined deflection' action 4of the prisms 31 and 36 when they yare in a position i-ntennedmte the position illustrated iii-Fig. 2 and the lposition of '/,cro defiection.

vlYhen. lfor example. the prism 31 produces' a deflection upward-and 'theprism 3G produces a deflection vobliq-u'ely upward and to the right, the actual position in the sc 'ene of the trace ofthe optical path is a spot at the lend',

of the resultant .obtained by'addin'g the two displacements vectorially.

' `When the prisms are nearly, but not ex.-

actly in the position illustrated'in Fig. 2, the change in the length of this resultant is slow. lVhen the two deflections are approximately at right angles to "each other, the

' Vchange in the length of the resultant is more spiral, thewhorls are more wi ely separat-ed.

At this part of the spiral the whorl's are nearly uniformly spaced. Near the center of the spiral, the spacing of the whorls is wider hut'here the spacing,r is also changing more rapidly.

At the outside of the spiral where the whoils are closely spaced, the linearvelocity of the spot of light on the screen, 'or of the correspondingr area in the view, is large. The illumination of the lscreen by the moving spot of light while traversing unit length of arc near the outside of thespiral is therefore small. Likewise the illumination 'of the Window 45 from that portion of the scenealong unit length of arc near the outside ofthe I spiral is small because that portion of the scene is traversed quickly.

` The increase in numher of turns of spiral and the increase in speed alongr the lines thus tend to offset each other, but they 'do not do so completely because 'the tivodo not change according to the same law. Best results are therefore obtained from-'those parts of the spiral i'vliere the 'spacing of the' lines is nearly uniform.4

. The stator l2 Fig. 1 and the stator 33A in-Fig. 2 are preferably provided with curvrent, from a common source. The two motors will, therefore, rotate in synchronism. By

temporarily increasing the retardation upon the disc 18 or the disc 37,-'the relative-rotation'of the prismsv 4 and 5 can be brought i into synchronism with the relative positions of the prisms 3l and 36. After this-has been accomplished,- the movements of the scanning device and of the reproducing device will -bc synchronous.

i Consequently, as ltheilight path in the scan ning .device trac-es a spira-l in vthe scene, the light beam in the reproducing,r device will -tiace a spiralupon the ground Vglass 6,01*,

if the reproducing deviceis -a projector ofthe' stereopticon type, itwili reproduce the spiral upon the screen before the spectators.. The

4. f l A i '1,689,847'

'two spirals correspond intime and position.v v i Because the brightness of the light fron: the lamp 1 is'made to correspond atfc'aeh ini stunt to the illumination of the photo-cell '4 6 the illumination of the'scr'een 'at' any point of the spiral traced thereon will correspond to the brightnesso that spot in the4 scene which correspond-sto theselecte'd pointer the screen. The distribution of the illumination on the screen will Vthereforecorrespond to the distribution of brightness in the scene and the result. of simultaneously tracing the two spirals is a reproduction of the vieu upon the screen. i l

Tl s reproduction-,- howl-ever, will not he' faithful because where the -whorls of the -spiral are close together, illumination vu on the screen-will not be in the proportiont ai correct reproduction requires.y In ordertc remedy this defect. certain portions onlyl oi the spiral are used either to illuminate the window 45 in Fig. 2 or to reproduce the picture on the screen. The simplest wa of ac'- coinplishingthis result is illustrated In Figs. 4 to 8.

In explaining the system illustrated in Fig. 4, they operation .vvill be described in terms ofthe projecting or 'recombining apparatus. It .is equally applicable to the scanning apparatus but mention thereof is, foi the most part, omit-ted to avoid confusion The dotted lines vof Fig. 4, represent thi boundary of the light beam from the point 51 which corresponds tothe-opening in'thf screen 3 of Fig. 1. The lenses 52 and 5 represent the action of the curved surfaces 0i the prisms 4 and 5. yThis action is accom plished by two separated lenses in order that lthe prism 56 ina-y be insert/ed' between them The prisms 5ft land 55 correspond to 'the prisms 4 and 5 in Fig. 1.l but there is a difference in their'd-esign. When the prisms 54 andl 55 are infthat relative position in Whicl'. they produce ininimum-deiection, the deflection is not zero. The 'maximum deflection i: obtained whenthe prisms are in the relativ( position illustra-ted in Figs, and thecorre spending light path is represented byth( dotted-lines a. The minimum deflection i: obtained 'when the osition 'of the prism 52 relative to'that 'of :ti e prism -54 differs fron the illustrated position-by 18G. The vpatl having -inin'inium deflection is illustratedbj the dotted lines b.

Bet-Ween the prisms .54" and 55 a double prism 56 is prof'vided. This prism is station' ary. Its upper hal-f tends to deiiect light Adown-Wa-rdly and its 'lower lhalf. tends fodelectlight upwardly.' In Fig. 5, the prism 5( is shown in fron-t ,view and its koutline i: represented as circular. This is 'nota v'neces sary configuration, but the outline' should be madeto conform to the shape of the mar-gir of the picture. Fig,...6, the prism is showr mum deflection.

`in section. The edges of the prism are. at `the l .`he up Ier dotted correspon s to the position upon the screen which would, if the prism 56 were absent, be

reached by' the light which, in fact, passes i through the upper half of the prism 56 and 58 into the same position 59.

the rectangle 58 represents the' corresponding position for the lower half of the prism 56. The action ofthe prism 56 brings the light which otherwise would reach the rectangle 57 into the 4central position 59 and the lower half of the prism 56 brings the light which would otherwise occupy the rectangle The tivo positions 57 and o8 are,consequent 1y, made to occupy the same central position 59, but the whorl-arcs therein fdo not coincide. This is 4.illustrated in Fig. 8 in which the closely'spaced arcs 61 correspond totheclosely spaced whorls near the bottoni 'of the position 58, While the closely spaced. arcs 62 correspond to the closely spaced whorls near the top of the rectangle 57.

The top of the picture, in botlrinstances, is at the 4top of Fig. 8. The two rectangles 57 and 58, therefore, correspond'to two scam nings of the scene orto two reconihinations thereof which can be superposedwitbout pro` ducing lack of registry. Moreover, the overillumination inthe rectangle 57 is brought into thesame position as the underillumination in tlxe a 1ecta1igle`58 and the overillumi nated part of the rectangle 58 is superp'osed lupon the less-illuminated part yof the rectangle 57. The two 'tend to correct-each other and,"consequently, unless the., rectangles are originally ositioned so that theye'xtend into portions o the spiral where the whorls are too-badly crow-ded, a satisfactory `reproductionmey be obtained over the w'hole'pieture.

vtfis possible, on the principle that any optical system is reversible, to explain the application of Fig. el to a scanning device by regarding the point 5l as the Window 45 'and thelight, asgtraveling from the righthand endof Fig. 4 toward the left. Such an explanation 'would' not, however, correspond' toa practical :I -rra'njelnent of the apparatus because -it would require certain parts to be too large.

An application of Fig, t tothe scanning apparatus which avoids this diti'ic-ulty may be rectangle 57 in Fig. .7

i-nade by regarding the point 51 as a. source of light in the landscape or y'other ob'e'ct viewedby the scanning apparatus. The' ens 52 then corresponds .to the lens 30, the 'prisms 54 and' 55 tothe prisms 31 and 3S andthe lens to the lens 40. JI lre prism 56 may be in-' sorted either between prism and lens 40 or betweentwo members of a. compound lens system equivalent tothe lens 40..

As the lenses 30 and 40 form au image of the view on the Wa-ll'of the casing 44 contain? ing window 45', so the lenses 52 and 53 form on the screens at the right of F ig. 4;- an image of the landscape or other view.

Also, as the motion of the prisms' 31 and 36 causes the-image to move over then'all, asso.

ciating thewindow ll'vvith points along a spiral in the image, so .the prisms 54 and 55 cause the image to move .on the screen, If a.

stationary point be selected .in the screen to correspond to window 45 the motion of the image over the screen will associate it with' points arranged alon paths in the ima e. The action of the prism A56, displacing tie image during two portions of each wllorl, the path traced in the moving image by the fixed point will not be a spiral but a net-work like that shown in F ig. 8.

The" apparatus illfustr-atediin Fig. 1 and Y Fig. 2 aords'only two complete .scannings of the view and recombinations of the picture for one cycle of the relative movement .of the prisms, while. the system illustrated in Figs.

4.- to 8 provides -four complete scannings in such a cycle. The number of lines traced 1n the picture for a single revolution of the pair of prisms when using Vthe system :illusts-1ted-4 in Figs. 4 to 8 is double the number obtained' by the system illustrated in Figs. l and 2.

Moreover, as is best shown in Fig. 7', the

illumination of the photocel l is not employedI for controlling the bri glit-njess upon thes'creen .durincr the Wholev of the revolution. It is,'

thereibre, possible to use 'the time when the 'optic-a1 system is in the position represented ov the riglithand and lefbhand lsegments of Fig. 7, for other purposes. For example, it

may bensed to con-trol s'ynclujoniz ing devices.

- In Figs. 9 to 12, .another 'example 4ofthis principle is illustrated in which,-ins'tead of one pair of prisms like the prism 56, three pairs are provided. The siii: prisms may very conveniently 'be built as a unit. lOYillustrate this unit.

The glass member tral portion 71 which .is optically inactive'and si; Wedgdsliaped vI imrginal portions 72 which i provide the 'prisma'tic effect. In order that the prisms72 shall not cause the light to break :up into colors, they are corrected by coi-nbin- Figs. 9 and.

70 comprises a lat'- cenxoo ies

Ving therewith, six prisms 73 of glass having a different index of refraction and f. different degree of dispersionfron) the glass 70. By

.so choosing the angles of the prisms 72 and 73',

that vthe dispersion is corrected .foreertain se- 1,639.84? `i I i 7 therefore withoutl'o', onto the face-95 irhere it is again reilected. in the same way, 'and it then emerges from the face 96.

The faces 94`and 95 are not parallel', consequentl the -exnerginlgy beam is not parallel toV the smlthrocgh the lenses 9.1. The difference in direction is such that theemer ing ray is diverted toward/the central part othe screen or of the view. A similar action is obtained in eachof the sixretlectin prisms. The result of theoptical system sloxvn in Fig. 13 is like the central part of Fig. 11 for 'the reasons which have. been already explained in connection with Figs. 910-and 12.

'The projecting apparatus illustrated in Fig. 1 or analogous projecting apparatus made according to Figs. 4, 12 or 13 maybe used for other purposes beside the reproduction of pictures upon the screen 6.

If the lamp 1 instead of varying its brilliance in accordance with the illumination at different points of the picture is of a steady brilliance, there may be substituted for the screen 6, a black and white picture; If the black and white picture-is a transpar-l ency, either the usual photographiencgative or a lantern slide, the projecting apparatus will cause the different points of this picture to be illuminated in turn, and the light which emerges from the transparency will yary in intensity according to the density of the transpareneyat each point.

' 'l The'light rvliiclikemergcsmfrin the transparency may be collected hy a lens or a lens system and delivered to a smallphoto-electric cell or it may beA received upon a large photo-electric cell or cells Without being first collected. The current controlled by such.

' photocell or photocells will then be like the current lcont-rolled by the photocell 46 -in F ig. 2, and may be used to control a. distant picturejreprod'ucing apparatus.

Instead of a transparency, the black and white picture may be opaque,- and the photocell and lens system to'fbe controlled by the light from the lamp 1 will then be upon the same side of the piet-ure as the lamp 1 and will be aiected -by the light reflected 'from the picture. light pas-ses over a dark part of. the picture, the photocell will be dark, and'when the light y from the lamp 1 passes over a White part-of the picture, the p hotocell will'be illuminated.

'se Fig. 1 .may be used as a picture-sending derice for either transparent or opaque black and white picturcs.

At intermediate shades, the pliotocell will be 'partly illuminated by the reflected light..

The reflected light may be received in a lens 'system to control a' small phot-occll, or a large phdtoeell or number ofv photoeells may be' used, as `with the transmitted light.

By this means, the apparatus, shown in It will be observed that-although Figs. 12

and 13v show complicated opti-cal arrange- When the-travelling spot of."

lrnents, the onlyfmoving partsl are the prisms -83-and 84. Also in the simpler system illustrated in Figs.' 1 and 2,' the corresponding prisms 4, 5, 3 1 and 36 'are the onl in'oving parts. The .system, th'erefore,has t e advan-vv the reproduction of the illumination througln" out the whole picture is very uniform.

The incommensurable relation between the speeds of the 'two rotating prisms gives the advantage that the consecutive images presented on the screen are not repetitions of the same points in the view but of points' closely adjacent thereto. This will result in greater -actual ldetail if the screen isla phot'ographio plate or in a greater perception of detail-if the screen 1s 'for visual observation. 1

Although I have described only a limitedvl number of modifications of my apparatus, it will be apparent to those skilled in the art that many changes come within the spiritof my invention and I, tl'ierefore, do not wish to be understoodv as indicating any limitations thereof except such as are required by the' prior art or expressed in the claims.

I claim as my invention:- f 1. In an opti-cal system for transmission of orrotating one of said devices, means for rotating the other of sai-d devices at a different speed dependent upon vthe speed-of. the first and means for adjusting the di-l'erence.

2. In an optical instrument, an electric motor comprising a' stator anda hollow' ro tor, a second hollowv ro'torin alignment with .the first, opticalprisms, vone in each rotor with faces across thc-axes thereof and -means whereby the speed ofone rotorfwiil differ from thatof the other.

i 3. In an. opt-ical instrument, an electric motor eomprisinga stator and a hollow rotor,-

asecond hollow rotor in align-nient with 'the lirst, optical prisin s,one in ca-ch`ro-tor with faces across the axes thereof and a brake retarding one of said rotors. A 4. In an optcal'systcm, stationary means for establishing-an optical path, lightdell-cc'ting -or establishing a second optical path' vcontinuoi-is therewith and at an .angle thereto,

means for rotating vsaid .lightsd'ellecting means to produce a rotation oi said' second optical path 'about the line ofthe lirst'opti' cal .pat-h and stationary 'lne-ans for dellccting light in said second optical 'pz'tth towardthe line o't said fixed optical path.

pictures, .two light-defiecting devices, means 5. lIn an optical systemstationary means forv establishing :1n-optical path, light-de optical' path about the line of -the-` first' opti-l cal path and means outside'the line ofsai fixed optical path for ldcflecting light tofA wards said line during at least a portion of f l thereto, the def-looting power of said devices 6..In an optical system, stati'onm'yl means for establishing an loptica lpath, light-deflect ing for establishing a second optical path continuous therewith and at an angle'thereto,

means for rotating said li ght-deilecting means to produce a rotation of said second optical 'path about the lineof the first optical path 'and means outside the line of said fixed optical path and arranged symmetrically about said line'jor,detlectliugr light towards said line d tiring atleast a portion of said rotation.

7. In a picture transmission system, an optical instrument having a window, means including moving optical parts for :establishing anoptical path connecting vsaid window with -`areas lyingalong a spiral and station ary light-detleoting means cooperating with said. first named means for'establishing an optical path connecting'said window with areasjn 'a locus similar to port-ions of said spiral'and displaced toward the center thereof.v

.8. In an optical instrument, a plurality of light-deflecting devi/ees arranged' .about an axis and eaehivso direotedas to deflect-lighttoward saidaxis .and means for producing a beam of light oblique to said axis and for dif recting'said beam upon each of said 4devices in turn'.

9. In an opti-cal system, for estiblishing al1-optical path having a. fixed direc.

tion, a pair of lightfdelecting devices associated with said. .path to produce a light path continuous therewith and at an angle .theretmthe deilecting power of said devices being unequal, whereby when they detlect'in pnpositodiretions the resulting deflection is i0. In 'an optical system, means,4 for establishing an optical path havinir` a. fixed dir-ec-l tion, a pair of light-deflectingdevieesassociated with said path to produce a light path con.-

ti nnous therewith and at an an Gle thereto, vthe detie'cting pon-eroi said devicesbeingunequal, 'whereby when they'detiect'in opposite directions the ,resulting deflection is finite and directions of 'said'diversions 4.11. .In an optical-system, means forest-,abs li's'hing an optical path having a fixed direcl 'ieans for progressively changing the relative tion, a pair of light-'detlecting devices asysp sociated with said path to'produee alight lpath conlrinuous the'i-.en'ith and, at an angle thereto, the ydieleeting power or' said devices being unequal, whereby Vx'v-hen they delect l vices arrange in opposite directioesfthe resultingdetleetio is vfiniteand means for progressively chang-l ing Athe relative directions Vof said diversions; leach of said directions being at, all times in a p14-ane through said. fixed direction.

A12. In 'an optical system, means for estab-l lieb-ing an optical path having a. fined'direcA d tion, a pair-of light-deflecting devices Aas.

sociated with said path tio produce a light oath continuous therewith Vand at ilnfan'gle being unequal, wherebywhen the ldeflect in opposite direct-ions the resulting t eile'ctiony is the delecting powers oftsa-id pair. of deilectin j .devices andv directed to deflect light towar' the line of said fixed path.

13; In an optical system, megms for establishing anoptical path having a fined direction, a pair of light-d'ctlecting devices .nssoeiated with .saidpat-li to pi'foduce a light 'path continuous therewith and atan angle thereto, the -df-:llectinfY 'power of said devices being unequal, wlierexliy'when they deflect in opposite directions. the resulting deflection is finite and a l-ura-li'ty 'of lighbdeflectinlfdm d about the line of said path and directed'to deflect light toward said line, each of said plurality having adetle'cting powerat least as greatest-he'difference of the detlecting'po'wcis 4oi" said pair' of deflectl ing devices. I

14. 'In an optical system, means :tor est-ab.- lishing adepti-cal pnt-h having a fixe-d direc-l tion, means fo' establishing ajn optical path continuous with said fixed path. and making an angle therewith, said mean-s .being movable --to vary both the plane and the size of said angle, 'whereby the second optical path ri'n'oves' Within a space bounded by two coaxial-cofres; the common axis being in alignment' with saidxed path: and a plurality of lightdey fleeting devices withinfsaidspace act-ing' to deflect-light toward said common axis.

l5. In an optical system, nieans -forestak inning an opten pat-h having a' ated aim tion, .means for 'estahlishing'an optical path4 1 l continuous with said iixed path making- 1 towardsaid'common axis, said llight deflecting devices bein" effective throughout-a portion only of the-circumferential"extent ofsaid In testimony whereo'l have Vhereunto .l

.my name'thi's 29th da; of April 1927. 

